Whip-stitching attachment for sewing machines



Aug. 1, 1939. .1. T. SANDBERG WHIP-STITCHING ATTACHMENT FOR SEWING MACHINES Filed Jan. 16, 1936 2 Sheets-Sheet l Aug. 1, 1939. J'. T. SANDBERG WHIP-STITCHING ATTACHMENT FOR SEWING MACHINES Filed Jan. 16, 1936 2 Sheets-Sheet 2 JAMES T SANDBERG Patented Aug. 1, 1939 UNITED STATES PATENT OFFICE WHIP-STITCHING ATTACHMENT FOR SEWING MACHINES James Torsten Sandberg, Stockholm, Sweden Claims.

The present invention relates to whip-stitching attachments for sewing machines whereby the so-called overcasting or overlooking stitching may be produced upon fabrics. and having amongst 5 its principal objects the provision of a device which is capable of being easily and readily applied to almost any standard or conventional sewing machine and which will, when so applied, cooperate with the sewing machine to carry a thread over the edge or edges of the fabric and interlock above and below alternately with the seaming thread or threads of the sewing machine.

Other objects of the invention will be in part obvious and in part pointed out hereinafter.

In order that the invention and its mode of operation may be readily understood by persons skilled in the art, I have in the accompanying illustrative drawings and in the detailed following description based thereupon, set out several embodiments of the same.

In the drawings:

Figure 1 illustrates in section a portion of a standard sewing machine having my attachment applied thereto and suspended from the bed plate of the sewing machine.

Figure 2 is a detail transverse section through the supporting frame of the attachment as applied to the bed plate of the sewing machine and illustrating by a top plan several of the movable parts of the attachment.

Figure 3 is a transverse sectional view taken through the supporting frame of the attachment showing the movable parts of the attachment in elevation and that portion of the supporting frame which is removed being illustrated in dot and dash lines, and

Figure 4 is a view similar to Figure 1 but illustrating how the attachment may be mounted upon the bed plate of a sewing machine.

Referring now more particularly to the accompanying drawings wherein like and corresponding parts are designated by similar reference characters throughout the several views, I have illus- 45 trated a portion of a bed plate 3 of a conventional sewing machine from which is supported a bearing 29 having journalled therein the ordinary shuttle shaft 21 and said bearing 29 has connected therewith an adjusting ring 30 which is mounted upon said shuttle shaft 21. A set screw is provided through said ring 30 whereby the shuttle shaft can be retained in a given position. A portion of the usual needle bar 23 of the sewing machine is also shown having detach- 55 ably connected thereto by means of a set screw 2|, a needle 22, which latter in the usual manner produces a stitching within the fabric 48, and the numeral 53 indicates the usual feed mechanism whereas, the numeral 2 indicates a guide plate for the fabric, which latter may be employed insteadof the usual presser foot of the sewing machine or the presser foot may be employed, provided it is arranged behind the needle 22.

The whip-stitching attachment embodying the present invention is capable of being applied to if a standard sewing machine having the foregoing parts and consists of a frame comprising a base portion 55a and a depending side arm la. This support is capable of being attached to the lower face of the'bed plate 3 by means of the attaching 1'5 screws 4 in the manner as is better illustrated in Figure 1 of the drawings. Journalled within the bearing 34a is a driven shaft Ilia, which latter has connected to its outer end a crank arm 20a so that with the rotation of the driven shaft Ilia, 20 this crank arm will be caused to rotate therewith. Pivotally connected to the outer end of this crank arm 20a as at [8a, is a rod I9a, which latter has transmitted thereto a reciprocating motion upon the rotation of the shaft Mia. The 25 outer end of the rod I'9a is pivotally connected as at Ila-to a bar 5a. This oar 5a is provided with an elongated slot 54a through which extends a guide pin Mia and this guide pin is secured to the depending arm la of the supporting 30 frame. One end of this bar 5a is provided with a right angular extension 8 which provides a holder for the whip-stitching thread carrier 1. This holder 8 extends through a slot 42' formed within the bed plate of the sewing machine so 5 that when a reciprocating motion is transmitted to the bar So, this Whip-stitching thread carrier 1 will be caused to move to and from the sewing machine needle 22. In order to cause this whipstitching needle to be fed alternately above and. 40 below the fabric 48, I provide a cam disc I5a which, by the rotation of thiscam disc l5a, an additional reciprocal movement will be transmitted to the bar 5a in a vertical direction. This cam disc la is keyed to a shaft I20. journalled 45 within a suitable bearing carried by the depending side arm la of the supporting frame and also keyed to this shaft lZa is a ratchet wheel 35a. Pivotally connected to the bar 5a as at l3a is a pawl I'Ia capable of engaging the ratchet wheel 35a, sothat during the reciprocating movement of the bar 511 in a longitudinal direction, the shaft l2a, together with the cam disc 15a carried thereby, will be caused to move in a clockwise direction. In order to maintain this arm 5a in direct contact with the cam disc 35a, I employ a spring 9a which latter is coiled about a supporting pin 59a secured to the depending section la of the supporting frame.

The shuttle shaft 21 of the sewing machine is provided with a worm gear 28, which latter is capable of meshing with the gear 36 carried by the driven shaft I 6a so that when the shuttle shaft of the sewing machine is set in motion, the driven shaft Ilia. will also be caused to rotate therewith. shaft of the sewing machine rotates with a number of revolutions equal to three times the number of sewing machine stitches and as the ratchet wheel 35a. is provided with six ratchet teeth and the cam disc l5a provided with three cams, a vertical reciprocating motion will be transmitted to the whip-stitching thread carrier 1 at every other longitudinal movement of this thread carrier 1.

In Figure 4 of the drawings, I have illustrated my whip-stitching attachment as applied above the bed plate 3 of the sewing machine, but when so applying this attachment, it is necessary that the base 55a of the supporting bracket as well as the bed plate 3 be provided with the openings 3| and 32 respectively, in order that a gear wheel may engage and mesh with the worm 28. This gear wheel 26 is carried by a stub shaft 25, which latter is journalled within a suitable bearing carried by the supporting arm I a in order that when the shuttle shaft 21 is set in motion, the same may be transmitted to the worm gear 28 and gear wheel 26. 7

From the foregoing, it is quite obvious that I have provided an attachment that may be easily and readily applied to the upper or lower face of the bed plate of a conventional sewing machine and when so applied, it will cooperate with the sewing mechanism of the machine so as to produce the usual whip-stitching of overstitching upon fabrics. When it is not desired to use this whip-stitching attachment, it may be readily removed from the bed plate of the sewing machine by removing the set screws 4, whereupon,

the sewing machine may be used for producing ordinary stitching upon the fabric.

The fabric guide 2 should preferably have an extension 6 in order to properly guide the fabric 48 when using my whip-stitching attachment but when using this cloth guide, it is of course necessary to either remove the usual presser foot of the sewing machine or permit the latter to be used upon the fabric only behind the needle 22.

Manifestly, the construction herein shown is capable of considerablemodification and such modifications as come within the scope of my claims, I consider within the spirit of my invention.

I claim:

1. The combination with a sewing machine In ordinary practice, the shuttle having a bed plate and shuttle shaft, of a whip stitching attachment comprising a supporting frame, means for detachably connecting said supporting frame to said bed plate, a whipstitching thread carrier and means for operatively connecting said whip-stitching thread carrier to said shuttle shaft.

2. The combination with a sewing machine having a bed plate and a drive shaft for the sewing mechanism thereof, of a whip-stitching attachment comprising a supporting frame, means for connecting said supporting frame to said bed plate, adriven shaft journalled upon said supporting frame, means for operatively connecting said driven shaft to said drive shaft of the sewing machine, a whip-stitching thread carrier, means for operatively connecting said whip-stitching thread carrier to said driven shaft whereby a reciprocating movement in a horizontal direction may be transmitted thereto and means for causing a reciprocal motion in a vertical direction to be transmitted to said whipstitching thread carrier during the reciprocation thereof in a longitudinal direction.

3. A whip-stitching attachment for sewing machines comprising a supporting frame, a driven shaft journalled upon said supporting frame, a whip-stitching thread carrier, a bar for supporting said thread carrier, and means for operatively connecting said bar with said driven shaft whereby upon the rotation of the latter a reciprocal movement will be transmitted to said thread carrier in vertical and horizontal directions.

4. A whip-stitching attachment for sewing machines comprising a supporting frame, a driven shaft journalled within said frame, a bar mounted for reciprocation upon said frame, a whipstitching thread carrier supported by one end of said bar, a rod connecting said bar with said ally and slidably connected to said supporting transmitted to said ,4!) driven shaft, a cam disc mounted for rotation frame, a whip-stitching thread-carrier supported by one end of said bar, a rod operatively connecting said bar with said driven shaft, a stub shaft journalled upon said supporting frame, a cam disc keyed to said stub shaft, means for resiliently retaining said bar in contact with said cam disc, a ratchet wheel keyed to said stub shaft and a pawl carried by said bar and having engagement with said ratchet wheel substantially as and for the purpose specified.

JAMES TORSTEN SANDBERG. 

